CMUSphinx collects over 20 years of the CMU research. All
advantages are hard to list, but just to name a few:

 + State of art speech recognition algorithms for efficient
   speech recognition. CMUSphinx tools are designed specifically
   for low-resource platforms
 + Flexible design
 + Focus on practical application development and not on research
 + Support for several languages like US English, UK English, French,
   Mandarin, German, Dutch, Russian and ability to build a models for
   others
 + BSD-like license which allows commercial distribution
 + Commercial support
 + Active development and release schedule
 + Active community (more than 400 users on Linkedin CMUSphinx group)
 + Wide range of tools for many speech-recognition related purposes
   (keyword spotting, alignment, pronuncation evaluation)

WWW: http://cmusphinx.sourceforge.net/